Pithoviruses Are Invaded by Repeats That Contribute to Their Evolution and Divergence from Cedratviruses
International audience Pithoviridae are amoeba-infecting giant viruses possessing the largest viral particles known so far. Since the discovery of Pithovirus sibericum, recovered from a 30,000-yr-old permafrost sample, other pithoviruses, and related cedratviruses, were isolated from various terrest...
Published in: | Molecular Biology and Evolution |
---|---|
Main Authors: | , , , , , , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2023
|
Subjects: | |
Online Access: | https://hal.science/hal-04299501 https://hal.science/hal-04299501/document https://hal.science/hal-04299501/file/msad244.pdf https://doi.org/10.1093/molbev/msad244 |
Summary: | International audience Pithoviridae are amoeba-infecting giant viruses possessing the largest viral particles known so far. Since the discovery of Pithovirus sibericum, recovered from a 30,000-yr-old permafrost sample, other pithoviruses, and related cedratviruses, were isolated from various terrestrial and aquatic samples. Here, we report the isolation and genome sequencing of 2 Pithoviridae from soil samples, in addition to 3 other recent isolates. Using the 12 available genome sequences, we conducted a thorough comparative genomic study of the Pithoviridae family to decipher the organization and evolution of their genomes. Our study reveals a nonuniform genome organization in 2 main regions: 1 concentrating core genes and another gene duplications. We also found that Pithoviridae genomes are more conservative than other families of giant viruses, with a low and stable proportion (5% to 7%) of genes originating from horizontal transfers. Genome size variation within the family is mainly due to variations in gene duplication rates (from 14% to 28%) and massive invasion by inverted repeats. While these repeated elements are absent from cedratviruses, repeatrich regions cover as much as a quarter of the pithoviruses genomes. These regions, identified using a dedicated pipeline, are hotspots of mutations, gene capture events, and genomic rearrangements that contribute to their evolution. |
---|